1. Field of the Invention
The present invention relates to an operational control for setting an actuating variable, more particularly a set point for a motor vehicle air conditioner, with a rotary knob, having at least two contact tracks and one spring wiper contact element that is in wiper contact with at least one contact track.
2. Description of the Background Art
Operational controls are often used in which wiper contacts are moved over contact tracks, for example in order to adjust a variable electrical resistance. The wiper contact element here can be fastened directly to the rotary knob of the operational control or can work together with the rotary knob. Such an operational control for actuating an air distribution flap in a motor vehicle air conditioning and/or ventilation device is known from EP 0 414 941 A1. In order to change the set point, a manually operated rotary control knob is moved through a certain angle and a wiper contact element is drawn over three concentric contact-making contact tracks. The wiper contact element is fastened to a separate disk that is mounted on the axis of the rotary knob. The disk carrying the wiper contact element is moved by a dog that is arranged on the rotary knob of the operational control. In order to compensate for the tolerances in the direction of the contact tracks, the ends of the wiper contacts are bent in a V-shape in the direction of the contact tracks. The wiper contact element is thereby rigidly attached to the rotary disk.
Another wiper contact element is disclosed in DE 101 11 400 A1. The wiper contact element here is also called a wiper, and is rotationally fixed to a gear that carries the wiper contact element. A printed circuit board is arranged directly beneath the wiper contact element. Contact tracks that the wiper contacts of the wiper contact elements slide over are applied to the printed circuit board. To improve the reliability of the contact, every wiper contact has two elastic wiper contacts. The wiper has two wiper arms, where wiper contacts are successively arranged in radial alignment on one wiper arm, while only one wiper contact is located on the other wiper arm.
From DE 43 19 543 A1 is known an automotive light switch with a rotary/push-pull switch accommodated in a housing for the parking and driving lights and interior illumination. In order to be able to perform additional light switch operations with such a switch, a regulating switch for headlight leveling and a regulating switch for the dashboard lighting are additionally installed in the housing. This automotive light switch is characterized in that each regulating switch constitutes an electrical switch with a resistance, adjustable by a spring wiper that is placed on the printed circuit board and is used to control the power consumption of electrical loads. The spring wiper here is arranged on the side of the printed circuit board opposite the adjusting wheel and is actuated by means of a rotatably mounted lever. The spring wiper here is mounted beneath the printed circuit board such that it can move.